Can Battery Storage And Solar Work Together? Arizona's Largest Utility To Find Out

Last week, Phoenix-based APS, Arizona’s largest utility, began testing a 1.5-megawatt-hour energy storage system. The shipping container-sized unit, developed by lithium-ion battery maker Electrovaya Inc., can dispatch power equivalent to 1,200 hybrid Prius sedans or 300,000 cell phone batteries. Here is a video with a description of how the unit works.

The energy storage system, located in Flagstaff, will see double duty over the two-year pilot. At its first stop, an electrical distribution substation, the unit will store electricity when demand and prices are low and dispatch it at peak, usually late afternoon and early evening, when demand surges. In about a year, the unit will be trucked a few miles away, to a neighborhood solar zone, to interact with a 500-kilowatt photovoltaic (PV) farm and cluster of rooftop solar arrays (more on this below).

Once installed at the Doney Park Renewable Energy site, home to the 500-kW PV farm, APS will use the energy storage system to supply power when solar output dips, as when a cloud passes overhead, and to help meet higher demand at peak after dark.

“One of the busiest times on our system is between 5 and 9 p.m. That’s when many customers get home from work, turn on the lights, the TV and the air conditioner. However, by that time, solar systems have largely stopped producing for the day,” APS Energy Storage Project Manager Joe Wilhelm said in a statement. “With storage, we can gather solar energy during the day and dispatch it in the evening.”